Patent GB-399791-A (GB)
Title: Improvements relating to multi-outlet electric switches
IPC: H01H67/26
Filed: 1932-03-31
Abstract: 399,791. Automatic exchange switches. SIEMENS BROS. & CO., Ltd., Caxton House, Tothill Street, and CHRISTIAN, D. A., Morven, Charlton Road, Charlton, both in London. March 31, 1932, No. 9285. [Class 40 (iv).] A unitary switch-mechanism of cross-bar type comprises ten switch members having access in common to ten levels each of ten outlets and a common control device adapted to select an idle or required outlet in any level for any of the switches and to control mechanically the completion of the corresponding connection. Circuit arrangements are described to illustrate the use of a switch-member as an ordinary group-selector, as a discriminating selector, and to connect directly together a calling line and a called line in a small exchange of fifty lines. Construction of switching mechanism, Figs. 1-6, 11. Each of the ten switch-members comprises a comb-like member 5, Fig. 3, mounted on brackets 7 so as to slide freely on a vertical rod 8, the free ends of the comb teeth fitting in wedge-shaped holes on an angle-iron member 13 similarly mounted to slide on a rear vertical rod. The ends of the vertical rods are fitted with screw caps having slotted heads engaging with T-members 4 on the main angle-iron structure 1, 2, the caps 9 fitting into the slotted ends of strips 10 to which are fitted guide members 11 engaging either side of the T-members 4. By loosening the caps 9 any switch-member may be withdrawn from the structure. Each tooth of the comb-member 5, representing a level of the switch-member, carries ten sets of resilient contacts. 52 and mounted adjacent to these and at right angles to the comb teeth are multiple strips 47, 48, 49 each representing an outlet in the level. These strips are carried by transverse bars 44 which also carry sliding members 45, 46 with contact-operating projections 55. The control-device unit is mounted on vertical rods 54 similar to the rods 8 and comprises vertical angle-irons 56, a top cross-member 67 carrying test relays T, and a bottom rectangular framework 57, Fig. 11, carrying control magnets. When a switch-member is taken into use its individual magnet M, mounted in a hole in a vertical plate-member 15, is energized moving a ratchet wheel 17 through one tooth so that the movement of a projection 21 frees a sliding member 24. This is moved to the right (as seen in Fig. 3) by spring 27, the switch comb 5 moving downwards one step due to the passage of knife-edges 82 over inclined surfaces on the top of member 24. By the movement of member 24 a pin 39, Fig. 4, falls into coincident grooves on 24 and a similar member 25, and operates contact springs FD. The downward movement of comb 5 brings the ends 53, Fig. 6, of contact springs 52 in front of projections 55 on members 45, 46. Impulses corresponding to a digit are then transmitted to magnet CM, Fig. 11, which rotates a shaft 64 with staggered cams 80 so that one of a series of flexible arms 79, Fig. 5, is positioned opposite a notch in a pivoted lever 76. Magnet SM now operates rocking shaft 65 (and at the same time knocking a holding pawl out of the ratchet of shaft 64) so that lever 76 in the selected level is tilted and a sliding bar 83 moves arms 71, which are connected over bars 73 to the test relays T, into engagement with the test contacts of the multiple outlet strips 47, 48, 49. When an idle outlet has been selected the corresponding magnet GM rocks one of five shafts 62 to left or right whereby an arm 72 pulls a sliding member 46 or pushes the complementary member 45. By this movement a projection 55 on the displaced member engages the end 53, Fig. 6, of the corresponding set of contacts on the lowered switch-member. The member 5 is then lowered a further step to bring the contacts 52 behind the projections on the contact-strips 47, 48, 49 so that when member 45 is released, connection between contacts 52 and the contact-strips is completed. The second downward step of member 5 is effected by the release of member 25 by a further operation of magnet M, and since the grooves in members 24, 25 no longer register, contacts FD are restored and at the same time contacts SD are operated by member 40, Fig. 4. At the end of conversation, magnet M releases and ratchet 17 is restored, detents 19, 32 having been withdrawn by projection 84 on member 25. Release rod 29 now moves to the right, Fig. 3, engaging arm 36 which by rocking shaft 37 causes the closure of contacts rs in the circuit of release magnet RM. This magnet rocks shaft 37 in the reverse direction causing arm 36 to restore rod 29 which takes with it sliding members 24, 25. The Provisional Specification states that there may be more than one control device associated with one mechanism. Modified construction, Fig. 13. The sliding members 45, 46, Fig. 5, are replaced by an arrangement for partially rotating the multiple which is in the form of conductors 87 carried on an insulating member 88 with a bent-over edge 89 around which the contact tips 91 are bent. The sliding bar 83 operated as in Fig. 5 acts on a bell crank 95 to position projections 98, 99, between tongues 100, 101, so that when shaft 62 is rocked in one or other direction the corresponding rotary member 92 to which the plate 88 is secured is rotated through a small angle bringing the tips 91 into the path of the switch contact members 90. Further slight modifications for particular uses of the selectors are referred to in the two final paragraphs. Group selector, Fig. 14. When a switch is seized its magnet M energizes in series with relay N in the common control circuit. The operation of M lowers the switch one step, the closure of contacts fd1 operating relays Q, U, whilst contacts fd2 connect up impulse relay A. Impulses are repeated to magnet CM, after which relay D releases, contacts cs1 over which it originally operated being released when shaft 64 takes its first step. A circuit is now completed for magnet SM in series with relay SN which connects up the test relays T<1> .. T‹. These relays which are differentially wound will not operate over ground on terminal 47 of a busy outlet due to the presence of a rectifier in the lead to bar 73 or over halfbattery potential which is present on bar 73 when another control circuit is holding the outlet. The test relay of the first idle outlet energizes and when relay U has relapsed completes a circuit for the corresponding magnet GM in series with relay P. Relay R is temporarily energized over an interrupter causing magnet M to release and re-energize owing to the change of current in its right-hand' (differential) winding. Contacts fd1, fd2 are now open releasing relays Q, A and the control circuit, whilst contacts sd close to lock magnet MAt the end of conversation, the release of M causes rod 29 to effect the closure of contacts rs so that when the control circuit is free, releasemagnet RM operates in series with relay RL, which maintains RM energized until the armature has completed its stroke. If there is no idle outlet in the level selected, relay B operates over back contacts of all the test relays, releasing SN, and operating BB which transmits one impulse to magnet CM. Magnet GM<0> is also operated so that connection is made to the tenth contact of the first level from which a busy tone is transmitted. If no impulses are received within a given time, relays S, Z operate successively, completing a circuit for SN and the switch is set to the tenth contact of the first level as in the case of all trunks busy. If a call is abandoned without dialling, the switch similarly sets itself to the tenth contact of the first level and then releases. Discriminating selector, Figs. 15 and 16. In this case there are three sliding members such as 24 and 25, the first closing contacts ft to associate the switch-member with the common control circuit, the second lowering the switch one step so as to bring some of its contact members into engagement with main-exchange junctions, whilst the third brings other contacts on to local trunks. When the switch is seized, relay AL(iii) operates in series with magnet M and relay N, and relays V, LO, JT, E are energized. Magnet M releases the first sliding member closing contacts ft1 .. ft4, and the operation of Q energizes magnet SM and relay SN causing the outgoing junctions to be tested in a manner similar to that described with reference to Fig. 14, the cam shaft 64, Fig. 5, being arranged to select the junction level when in its normal position. When an idle junction has been selected relay P causes the temporary release of magnet M so that the switch is lowered its first step to connect up the selected junction. Relay P also energizes relays F, G, releasing SN. Impulses are transmitted to magnet CM as in Fig. 14 and if the first digit is 1 or 2 denoting a local connection, relay L operates over contacts sr closed by a sliding bar 83, Fig. 5, connecting battery over high resistance to the a-wire. Relay H energizes, releasing relay JT and the seized junction, and an idle outlet in the local level is seized, the operation of relays P, F, then causing the switch to take its second step. If the first digit is 4 .. 0 denoting a mainexchange connection, relay J operates connecting up R which causes the switch to move through its second step, closing contacts lt, opening contacts ft, and releasing the control circuits. If the first digit is 3, discrimination is completed at the next local selector which acting in a similar way to that shown either connects high-resistance battery to the a-wire to release the junction as above, or lowresistance battery, which energizes relays Y, H releasing LO and the local connection. Small exchange, Figs. 17 and 18, in which calling and called lines are connected together over the same switch-member. Each of the fifty lines is multipled to one of the upper five levels for outgoing calls and to one of the lower five levels for incoming calls. The vertical bars (7